DESCRIPTION (Applicant's Description) Recent technical advances in molecular biology have led to increased understanding of the nature of the genetic and epigenetic changes that occur in the development of skin tumors. These advances are greatly improving and expanding our concepts of the mechanisms by which normal cells progress to malignancy. The role of both intrinsic genetic factors and external modifiers, i.e., chemical carcinogens, ultraviolet light and tumor promoters, are now being elucidated. The goal of this conference will be to provide a forum for exchange of the most recent and relevant information on the biological, cellular and molecular changes that occur during skin tumor development. The principle emphasis of this conference is on elucidating the changes in genes and gene expression that play a role in the development of skin cancer. Sessions will focus on understanding the genetic factors that can influence skin cancer susceptibility, how alterations in normal cell signaling and proliferation affects the expression of particular genetic alterations, and how intrinsic and extrinsic factors can modify the neoplastic process. This conference is significant for two reasons. First, it is through investigations into the mechanisms of skin cancer that many hallmark discoveries have been made that are applicable to many if not all human epithelial tumors. Among the most notable was the development of the multistage concept of tumor development. Second, it is anticipated that a sharing of ideas and information through an interactive conference format will foster the creation of new ideas and concepts and thus lead to the improved strategies for cancer intervention and prevention. This conference is intended to bring together individuals from the major laboratories in Europe, Japan and the United States that are actively engaged in research on the mechanisms of skin cancer in order to foster the needed greater interaction and communication.